DESCRIPTION (Applicant's abstract): The period of life spanning the middle 20's and early 30's is critical in determining an individuals contribution to and functioning within the broader society. As individuals progress from early to mature young adulthood, they form and solidify their roles as spouses, parents, and workers. At the same time, eighty-seven percent of men and 83 percent of women who will ever be drug abusers or drug dependent experience onset of problems before age 30, the vast majority of them between the ages of 20 and 30. Typically, substance use began when these individuals were adolescents. Capitalizing on the opportunities afforded by the unique RAND Adolescent/Young Adult database. We propose a program of research to determine how fluctuations in substance use and changes in social roles are related, focusing on two critical periods of young adulthood: age 24 (early young adulthood) and 30 (mature young adulthood). Our specific aims are to: 1) Explore the patterns of substance use, stability and change over a period of 17 years and examine the risk and protective factors for problem USE at ages 18, 24 and 30; 2) Test predictive relationships between adolescent and young adult substance USE and family formation and functioning at ages 24 and 30, including marriage and divorce, parenting, and domestic violence; and 3) Test predictive relationships between adolescent and young adult substance USE and educational attainment, occupational choice, and labor market participation at ages 24 and 30. Building on our past and current studies of substance use antecedents and consequences, we propose to supplement the existing panel data (which includes 8 waves between age 13 and 24) with a follow-up survey at age 30 plus secondary data on school and community factors at several time points. This panel covers individuals at all economic levels, persons from diverse racial/6thnic backgrounds, and school dropouts. The resulting database will allow us to assess the unique contributions of individual and community factors to early and mature young adult behavior.